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October 14, 2018
10/14/2018 3:30:00 PM - 10/14/2018 5:30:00 PM
Room North, Hall D, Area B
Performance Assessment of the PMD-200 in Subjects Requiring Surgery Under General Anesthesia
Virginia Horne, M.D., Borzoo Farhang, D.O., Alexander Friend, M.S., Max Breidstein, B.S.
UVM Medical Center, Burlington, Vermont, United States
Disclosures: V. Horne: None. B. Farhang: None. A. Friend: None. M. Breidstein: None.
INTRODUCTION: Management of analgesia under general anesthesia (GA) is mainly determined by the clinical expertise of the anesthesiologist. Sufficient analgesia is critical to avoid complications of the sympathetic over-activation, but restriction of opioids to the minimum dosage is desirable to decrease the risk of opioid-induced hyperalgesia, hypotension, respiratory depression, delay in return of bowel function, or delay in discharge. Typically, opioids are titrated based on the clinical signs of sympathetic stimulation such as increase in heart rate (HR), mean arterial blood pressure (MAP), diaphoresis, or movement. To assess nociception during GA, we used a novel multidimensional measure of nociception, the nociception level (NOL) index, derived from the nonlinear composite of HR, HR variability, amplitude of the photoplethysmogram (PPG), galvanic skin response (GSR, fluctuations in skin conductance), concurrently with their time derivatives. OBJECTIVE: To investigate the ability of NOL index acquired via the PMD-200 system (Medasense Biometrics Ltd., Ramat Gan, Israel) to detect noxious stimuli of different intensities during GA. METHOD: Following IRB approval, ten ASA II-III patients (4 male, 6 females, mean age 39.4) scheduled for elective laparoscopic surgery under GA were enrolled in this prospective, observational study; all participants gave written informed consent. GA was induced and maintained at the discretion of the anesthesiologist. Patients´ PPG and GSR as well as the physiological parameters were extracted and compared to the NOL index. Four intraoperative events were examined: severe noxious stimuli (intubation); moderate noxious stimuli (incision or insertion of trocar); mild noxious stimuli (skin closure, scrubbing); and non-noxious stimuli (a 1-min interval within a 3-min window of absence of noxious stimulation). RESULTS: Preliminary analyses of the first 10 patients revealed that the NOL index successfully differentiated noxious and non-noxious events (P<0.001). The differences in the mean NOL values among the 4 event groups were statistically significant (P = 0.03), and significant increase in the median NOL index above the threshold of 25 was observed following severe (11.6 to 41.7, p=0.038), moderate (11.4 to 35.1, p=0.007), and mild noxious stimulation (4.3 to 22.7, p=0.003) in all patients (figure 1). NOL index and MAP remained unchanged in response to non-noxious stimuli. Furthermore, in 1-3 occasions for nine patients there were significant changes in NOL index, while the MAP increased above 100 mmHg or remained unchanged, and the NOL index could provide differential and complimentary information about the nociceptive behavior. CONCLUSIONS: These preliminary results validated the NOL index in identification and discrimination of noxious/non-noxious stimuli as well as grading the nociception response by intensity of stimulus. Non-invasive monitoring of NOL index reflected nociceptive response during GA and therefore may indicate the nociception/anti-nociception balance. Moreover, in cases where the mean arterial pressure increased above 100 mmHg, NOL index could provide alternative and complimentary information about the nociceptive state of the patients under GA and guide the choice of opioids versus sympatholytic administration.
Figure 1

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